1. Description of the Prior Art
Gaseous fuel carburetors useful for applications in internal combustion engines for motor vehicles have been exemplified numerous times in the prior art literature and in commercial embodiments. Descriptions of typical prior art examples can be found in U.S. Pat. Nos. 2,311,315 granted to Smith on Feb. 16, 1943; 2,387,862 granted to Smith and Paxton on Oct. 30, 1945; 3,948,224 granted to Knapp and Nesbitt on Apr. 6, 1976; and 4,308,843 granted to Garretson on Jan. 5, 1982. In accordance with these and other prior art teachings, various control systems have been proposed by which the mixing of gas fuel with engine intake air is regulated so as to produce a desired charge for the engine having a proper fuel-to-air ratio for efficient combustion under varying load demands of the engine. An objective of any such gas fuel metering system (normally characterized as a carburetor) is to provide a charge for the engine that is proper for varying engine operating conditions, particularly under circumstances where enrichment of the fuel is rapidly needed to meet the demand for higher engine torque or speed by the operator of a vehicle in which the engine is installed.
While the prior art suggests various means for controlling the fuel/air ratio of a gas fuel supply system used for internal combustion engines, including systems utilizing vacuum signals having as their source intake manifold pressure of the engine, such systems tend to be complex, costly and difficult to maintain in proper adjustment in the environment of an internal combustion engine. Moreover, such systems usually require careful calibration for each engine and they are not generally adapted to be simply retrofit on existing engines as a substitute for an existing liquid fuel carburetor or as an auxiliary carburetor for use in conjunction with existing liquid fuel carburetors constituting original engine equipment.